Power consumption
We measured total system power consumption at the wall socket using an Extech power analyzer model 380803. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. We tested all of the video cards using the Asus P5N32-SLI SE Deluxe motherboard, save for the CrossFire system, which required a different chipset. For that system, we used an Intel D975XBX motherboard.

The idle measurements were taken at the Windows desktop. The cards were tested under load running Oblivion using the game's Ultra Quality setting at 1600x1200 resolution with 16X anisotropic filtering.

The X1900 GT's idle power consumption isn't bad, but it follows the trend of R580-based graphics cards chewing up quite a bit of power under load. In this case, the X1900 GT requires about 35 more Watts than the GeForce 7900 GS to run the same game at roughly the same performance level.

Noise levels
We measured noise levels on our test systems, sitting on an open test bench, using an Extech model 407727 digital sound level meter. The meter was mounted on a tripod approximately 14" from the test system at a height even with the top of the video card. The meter was aimed at the very center of the test systems' motherboards, so that no airflow from the CPU or video card coolers passed directly over the meter's microphone.

You can think of these noise level measurements much like the system power consumption tests above, because the entire systems' noise levels were measured, including CPU and chipset fans. We had temperature-based fan speed controls enabled on the motherboard, just as we would in a working system. We think that's a fair method of measuring, since (to give one example) running a pair of cards in SLI will cause the motherboard's coolers to work harder. The motherboard we used for all single-card and SLI configurations was the Asus P5N32-SLI SE Deluxe, which on our open test bench required an auxiliary chipset cooler. The Asus P5W DH Deluxe motherboard we used for CrossFire testing didn't require a chipset cooler, so those systems were inherently a little bit quieter. In all cases, we used a Zalman CNPS9500 LED to cool the CPU.

Of course, noise levels will vary greatly in the real world along with the acoustic properties of the PC enclosure used, whether the enclosure provides adequate cooling to avoid a cards' highest fan speeds, placement of the enclosure in the room, and a whole range of other variables. These results should give a reasonably good picture of comparative fan noise, though.

We measured the coolers at idle on the Windows desktop and under load while playing back our Quake 4 nettimedemo. The cards were given plenty of opportunity to heat up while playing back the demo multiple times. Still, in some cases, the coolers did not ramp up to their very highest speeds under load. The Radeon X1800 GTO and Radeon X1900 cards, for instance, could have been louder had they needed to crank up their blowers to top speed. Fortunately, that wasn't necessary in this case, even after running a game for an extended period of time.

In spite of its higher power draw, the X1900 GT manages to turn in lower noise levels on the decibel meter. This is no fluke, either; our ears observed the same quiet performance from the X1900 GT.

I believe there are two main reasons for the X1900 GT's subdued aural profile. First, the card's cooler really is larger and more substantial than the one Nvidia supplies on its competing products in this class. Notice how the GeForce 7900 GTX, with a big, dual-slot cooler and the same power draw under load as the Radeon X1900 GT turns out to to be the quietest card of the bunch. Bigger, better coolers matter. Second, ATI and Connect3D allow this card to grow very hot before turning up the blower speed on the thing. The X1900 GT ran our Quake 4 torture test for quite a while without ever kicking its blower into high gear. That's great for the ears, but don't put your finger on the card, or you risk burning yourself.